class Solution {
public:
    int rob(vector<int>& nums) {

       int n=nums.size();
       return max(nums[0]+rob1(nums,2,n-2),rob1(nums,1,n-1));
    }
    int rob1(vector<int>& nums,int left,int right) {
        if(left>right)
            return 0;
        vector<int> f(nums.size());
        vector<int> g(nums.size());
        f[left] = nums[left];
        for(int i=left+1;i<=right;i++)
        {
            f[i] = g[i-1]+nums[i];//进入i
            g[i] = max(g[i-1],f[i-1]);
        }
        return max(f[right],g[right]);
    }
};